This invention relates to data switches, and more particularly to multi-user keyboard, video, and mouse (KVM) switches.
Keyboard/mouse/video switches are well known for allowing a keyboard, workstation and video monitor to interact with a selected one of several computers. Although known KVM switches take a variety of forms, their essential purpose is to allow a workstation (consisting of, generally, a keyboard, mouse and monitor) to interact with a selected computer such that the computer receives and transmits understandable signals to and from the various workstation components regardless of the data protocol schemes employed by either the selected computer or the workstation devices. Typical KVM switches allow the user of the workstation to switch access between various ones of the number of associated computers.
The KVM switch box will typically have at least one port for the workstation devices to provide and receive signals from the switch, together with a series of computer ports by which each of the associated computers is linked to the switch. Most KVM switches employ a single user (single workstation) architecture in which a single keyboard, video, and monitor may access multiple numbers of computers, but the prior art is not limited to such architectures. Matrix type KVM switches are also known which provide switch or router type functions to connect any one of several associated workstations with any one of several associated computers.
Thus, KVM switches, some of which are matrix switches, are manufactured commercially by companies including Cybex Computer Products Corporation of Huntsville, Ala., Apex PC Solutions of Washington, The CCC Group of England, and Rose Electronics of Houston, Tex.
The present KVM switch provides an alternative architecture for multi-user, multi-computer connections that provides substantial advantages over prior architecture. In particular, the present KVM switch is characterized by a single KVM processor by which many of the multiple users can access one or more of the different computers, even simultaneously to any one given computer. The single processor provides for processing efficiencies and permits the preferred KVM switch to poll the user ports and computer ports via interrupt routines in order to obtain next available data to be switched.
In an example embodiment, the KVM switch also provides access to a user that is local to the switchbox and access to another user that is remote from the switchbox. In this alternative embodiment, the remote user communicates with the switchbox via, preferably, a CAT5 cable communicating with an integrated extension product within the KVM switchbox and an external extension product near the user station. Of course, the KVM switch can employ fiber optic cable, an integral waveguide, or a wireless connection in lieu of the CAT5 connection. The CAT5 connection may be arranged in accordance with U.S. patent application Ser. No. 08/971,223 now U.S. Pat. No. 6,185,643, incorporated above.
With the single processor architecture, other special features may be employed in the preferred KVM switch. These include the use of a FLASH memory to load several different default on-screen display activation sequences and OSD configurations into the KVM switch. That is, different KVM switch types can call the pop-up on-screen-display menu using different keystroke sequences. The presently described FLASH memory contains predetermined sequences that may be used for calling up on-screen-displays in accordance with predetermined keyboard sequences, which sequences (and other configuration parameters) can be charged by flash memory download.
The single processor also provides solutions to particular issues associated with providing simultaneous access by two users to multiple computers. For example, the preferred embodiment includes solutions for a single processor to monitor keyboard and clock lines for eight different computer ports. Further, the preferred embodiment employs provisions for dealing with different kinds of mouse protocols that may exist when two different mouse controllers are connected to a common computer. In the preferred embodiment, the KVM switch employs a hierarchical ranking system for the mice, as described in U.S. patent application Ser. No. 09/564,794, now U.S. Pat. No. 6,256,014 filed on May 5, 2000, entitled xe2x80x9cMouse Ranking Systemxe2x80x9d.
These, as well as other objects and advantages of this invention, will be more completely understood and appreciated by careful study of the following more detailed description of a presently preferred exemplary embodiment of the invention taken in conjunction with the accompanying drawings, of which: